JPS6221428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for notifying a protocol error detected by a protocol conversion device during protocol conversion.

Data that is constructed by interconnecting various devices such as computers, terminal devices, and pre-processing devices via transmission lines that comply with the network architecture that specifies the logical structure and protocols (communication rules) related to communication. In a communication network, a device that converts protocols for connecting devices with different network architectures in order to connect devices based on different network architectures and enable communication. It was necessary to do it through .

Traditional data communication networks, especially network
In a data communication network constructed by connecting various devices that are not based on any architecture, each device is connected via a relay device, each protocol is terminated at the relay device, and each message is transmitted in units of messages. By assembling and disassembling the relay equipment, the ingress and egress lines of the relay equipment were made independent, allowing normal communication between each equipment. When such a system is applied to protocol conversion in communication between devices based on different network architectures as described above, the following problems occur.

In other words, the network architecture defines multiple protocol layers, and when the above-mentioned method is applied, the protocols of all layers are once terminated in the protocol converter and then assembled and disassembled in units of messages. It becomes necessary to carry out processing. Therefore, the relay delay due to this processing time increases, and the buffer for assembling the message also increases the holding time, so it becomes necessary to have a large number of buffers.

Recently, protocol conversion methods have been proposed to avoid this type of drawback. According to this conversion method, when devices based on different network architectures are interconnected and communicated via a protocol conversion device, only high-level protocols are used end-to-end, and Conversion is performed in units of data blocks, and the low-level protocol is once terminated by a protocol converter, and by assembling and disassembling message units, they are made independent on the input and output lines.

Note that the high-level protocols are layers 5 to 5 in the OSI reference model of the ISO (International Organization for Standardization).
This corresponds to a layer 7 protocol, and lower level protocols correspond to layer 1 to layer 4 protocols. Here, the OSI reference model is layer 1
(physical layer), layer 2 (data link layer), layer 3 (network layer), layer 4 (transport layer), layer 5 (session layer), layer 6 (presentation layer), layer 7 (application layer) It has a seven-layer structure.

The present invention provides, in such a protocol conversion method, a high-level protocol error detected by a protocol conversion device, which is managed by both end devices, and is notified without mutually contradicting each other. This invention provides a protocol error notification method in protocol conversion that achieves consistent error notification and speeds up error recovery. A detailed explanation will be given below with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a data communication network to which the present invention is applied. In the same figure, A ₁
. . . A ₆ are devices conforming to network architecture “a”, and B ₁ to B ₇ are devices conforming to network architecture “b”. As mentioned above, these devices A _i and B _j include computers, terminal equipment, etc. A data communication network is constructed by arranging pre-processing devices and the like at appropriate positions and connecting them through transmission lines. In this configuration example, network architecture “a” and “b”
A protocol conversion function for performing protocol conversion between devices A ₂ and A ₄ is added. This protocol conversion function is used between devices A ₂ and B ₂ , and between devices A 2 and B 2.
In some cases, it is installed independently as a protocol conversion device between _A4 and _B4 ... _B5 . The second sequence chart for explaining the processing operation of the present invention
In the figures and in FIG. 3, a protocol conversion device C is shown arranged between the devices A _i and B _j .

In such a data communication network, when communication occurs between device A _i and device B _j , protocol conversion between network architecture "a" and "b" is performed on the device A _i side. This is executed by the protocol conversion function added to the protocol conversion function or the protocol conversion device C. At this time, as mentioned above, the target of conversion is only the high-level protocols that provide inter-process communication functions of each network architecture, and lower-level protocols are terminated by protocol conversion device C etc. and will not be converted.

Furthermore, when a protocol error occurs in a high-level protocol such as the one mentioned above, the recovery process is generally performed on a device that is functionally larger in order to reduce the load and prevent contention in the recovery process. For example, the host computer) side is given responsibility for recovery and is made to perform error recovery processing, while the other device (eg, terminal device) is prevented from performing recovery processing. This recovery process includes resynchronization, data retransmission, and communication interruption.

Here, the error recovery process is executed based on the content of the detected protocol error,
Therefore, for devices that are responsible for error recovery,
It is necessary to notify the occurrence of an error and its contents, and it is stipulated that the protocol conversion device that detects the error notifies the device responsible for error recovery of the contents. Further, when a protocol error occurs, it is necessary to stop the sending process, and the protocol conversion device is specified to notify the sending side device of the occurrence of the error as well. Hereinafter, with reference to FIGS. 2 and 3, a method for notifying a protocol error will be explained for cases in which a device responsible for error recovery is transmitting and receiving data, respectively.

FIG. 2 shows a case where a device B _j that has error recovery responsibility is sending data to a device A _i that does not have recovery responsibility. The protocol conversion device C performs the protocol conversion between ``b'' and ``b''. Protocol conversion device C converts the protocol of the message from device B _j in units of data blocks in a high-level protocol and transfers it to device A _i .
Device A _i checks the received data block in units of messages, and returns an acknowledgment if it is received correctly. This acknowledgment is from protocol converter C.
The protocol is converted and returned to device B _j . 1
Device _Bj , which has been on standby after sending the message, starts sending the next message upon receiving the acknowledgment. However, it is generally possible to asynchronously transmit the message and receive the response.

Protocol conversion device C detects protocol errors in units of data blocks, and when an error is detected, returns a negative response to device _Bj . The details of the error detected by the protocol conversion device C are added as additional information to this negative response, and the device _Bj , which is responsible for error recovery, is notified of the occurrence of the error and its details. Upon receiving this negative response, device B _j stops transmitting the message that is in progress and proceeds to the recovery process described above. The message partially received by device A _i is discarded by the error recovery operation of the higher-level protocol.

In FIG. 3, the flow of data is reversed to that in FIG. 2, and is shown in the case where data is sent from a device A _i that does not have recovery responsibility to a device B _j that has recovery responsibility. In this case as well, the high-level protocol is converted by the protocol conversion device C not in units of messages but in units of data blocks, and is transferred from device A _i to device B _j . If protocol conversion device C detects a protocol error during this process, it first sends a negative response to device A _i with the detected error content as additional information. When the sending device A _i receives this negative response, it stops sending the message that is being sent, and waits until it is requested to send the message again through the recovery process. At the same time, protocol conversion device C sends an error notification command to device B _j . This error notification command is to notify device B _j that is responsible for error recovery of the occurrence of a protocol error and its contents. Device B _j that receives this command returns an acknowledgment to protocol conversion device C and performs error recovery. Move to processing.

As described in detail above, in the present invention, regarding an error detected during protocol conversion, information notifying the occurrence of the error and its contents is sent to the device responsible for error recovery. Processing contention can be prevented, the load can be reduced, and the consistency of state management in both devices and the speed of error recovery can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of a data communication network to which the present invention is applied, and FIGS. 2 and 3 are sequence charts for explaining the error notification system according to the present invention. A ₁・A ₂ , ~ _{A 6} , A _i , B ₁ , B ₂ , ~B ₇ , B _j ...
Various devices constituting the data communication network, C...protocol conversion device.

Claims (1)

[Claims] 1 Provision of inter-process communication function, etc. Protocol conversion function that converts only high-level protocols end-to-end in units of data blocks, and terminates low-level protocols to make each ingress and egress line independent. In a protocol conversion method that enables devices based on different network architectures to communicate with each other via a ,
An error notification method in protocol conversion characterized by notifying a device responsible for error recovery in the communication and a data transmitting side, respectively.